content: /*
   * Copyright 2017 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.reactive4javaflow.impl;
  
  import hu.akarnokd.reactive4javaflow.fused.FusedSubscription;
  
  import java.util.concurrent.Flow;
  
  public enum EmptySubscription implements FusedSubscription<Object> {
      INSTANCE
      ;
  
      @Override
      public Object poll() throws Throwable {
          return null;
      }
  
      @Override
      public boolean isEmpty() {
          return true;
      }
  
      @Override
      public void clear() {
          // deliberately no-op
      }
  
  
      @Override
      public int requestFusion(int mode) {
          return ASYNC;
      }
  
      @Override
      public void request(long n) {
          // deliberately no-op
      }
  
      @Override
      public void cancel() {
          // deliberately no-op
      }
  
      public static void complete(Flow.Subscriber<?> s) {
          s.onSubscribe(INSTANCE);
          s.onComplete();
      }
  
      public static void error(Flow.Subscriber<?> s, Throwable ex) {
          s.onSubscribe(INSTANCE);
          s.onError(ex);
      }
  }
  